Google’s parent company Alphabet is developing a method using vats of heated salt and cooled liquid to store renewable energy, Bloomberg reported. The company’s X research lab is leading the project, known as Malta.
As huge renewable energy projects are announced seemingly every day as prices for wind and solar drop, one big and well-documented problem remains – peak power consumption does not synchronise with the brightest sun or fastest wind, so unneeded energy is frequently wasted. Power grids need new storage methods to save the energy for when it is needed, allowing renewable sources to truly challenge fossil fuels’ grip.
The new method, which is reportedly in an early stage of development, uses electricity to heat or cool respective parts of the system. Then, when energy is needed, hot air from the salt and cold air from the antifreeze or hydrocarbons rushes together through a turbine, converting the energy back into electricity. The salt could potentially keep its temperature for days, Bloomberg reported, meaning the system could be tapped when needed.
The idea is “right on the money,” said engineer Dénes Csala from Lancaster University to Professional Engineering. Other proposed storage methods are often untested and too expensive on a large scale, he said. “The learning curve isn’t actually that steep in terms of integrating it back into the electricity system, as it would be with batteries, which also still have a cost burden attached with them.”
Some solar power plants in Spain and Arizona already use molten salt to store energy, said Csala, who claimed the method is “further down the innovation S-curve” than large-scale storage with “very hyped” lithium batteries.
“It is true that for small-scale, meaning for a car or a home… lithium batteries are a perfect solution,” he said. “However, they are expensive. On this scale, you don’t really start feeling that difference so steeply but when you go on a large scale – a MW scale, so a thousand times bigger – then the price becomes prohibitive. That is why I believe we haven’t seen any large-scale lithium battery storage projects yet.”
The new Alphabet system is promising because it is designed for large-scale storage from the start, said Csala. The salt method could also be longer-lasting than batteries and cheaper than other storage, X executives and researchers told Bloomberg.
The team is now looking for partners to build, operate and connect a prototype to the grid.